The present invention is broadly concerned with apparatus for separating water and gas from crude oil at an oil field site and, more particularly, to a prefabricated turnkey apparatus for such separation activities.
Crude oil is produced from oil wells drilled into the ground until they penetrate oil bearing layers beneath the surface. Although some oil deposits are under pressure and “gush” to the surface, a more typical situation is that the oil must be pumped to the surface for recovery. A common type of mechanism used to pump oil to the surface is referred to as a pump jack. A pump jack includes a walking beam pivotally supported on a frame and having a rear end connected to a crank arm with a counterweight. A front end of the walking beam has a “horse's head” shaped bearing structure which is connected by a cable, known as a bridle, to a polished sucker rod, or a string of such rods, extending through a seal or stuffing box down the well casing to a down hole pump mechanism. The down hole pump includes a set of check valves, commonly referred to as a lower standing valve and an upper traveling valve. Rotation of the crank arm by a motor geared thereto produces a vertically reciprocating motion in the sucker rod which repeatedly lowers and raises the down hole pump through the oil bearing zone. The action of the check valves causes the down hole pump to gather a quantity of oil on each pass and urge it above the down hole pump. Eventually the gathered oil is pushed to the top of the well casing by the pumping process and enters oil collection or well stream piping near the surface.
Crude oil produced from an oil well is typically an emulsion of a mix of petroleum liquids, water and/or aqueous solutions, and gases. The water component often includes various amounts of salt, while the gas is mostly methane. The petroleum and methane components have commercial and industrial value and are typically separated from the emulsion and stored for delivery to buyers of these products, although the methane gas is sometimes used as fuel for operating the oil pumping rig or other machinery associated with the oil well. The water or salt water is separated and may be pumped back into the ground locally or accumulated in an tank and transferred to other sites for pumping into the ground or other uses.
Often, the crude oil emulsion produced from a number of wells in a field is accumulated and processed in a separator plant which is constructed near the wells and whose separating capacity is related to the volume of crude oil production from the wells. Conventional separator plants are constructed in place near the oil well site, using conventional construction techniques. One aspect of many oil wells is their temporary nature. When the economically recoverable oil in a given deposit is depleted, the well or wells are capped, and the pumping machinery is removed, refurbished and reconstructed for service at another location, or scrapped. Once an oil well site is deactivated, the separator plant is no longer needed, and the components of the separator plant are also removed, refurbished and reconstructed, or demolished and scrapped.